Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide the cracking-preventing structure for the wharf surface layer, which can obviously reduce the shrinkage and tensile stress of wharf surface layer concrete under the action of strong bottom constraint, avoid various types of cracks of the surface layer concrete, and has the advantages of simple form, convenient implementation and high cracking control cost performance.
In order to solve the problems, the invention provides an anti-cracking structure for a wharf surface layer, which comprises a composite concrete layer, wherein the composite concrete layer is arranged on a hard substrate of a wharf and comprises a low-shrinkage concrete layer and a fiber concrete layer, and the low-shrinkage concrete layer is arranged between the hard substrate and the fiber concrete layer.
Preferably, the low shrinkage concrete layer consists of cement, fly ash, slag powder, river sand, broken stone, mixing water, a water reducer, a shrinkage reducing agent and an expanding agent, wherein the cement dosage is 171kg/m < 3 > -180 kg/m < 3 >, the fly ash dosage is 95kg/m < 3 > -100 kg/m < 3 >, the slag powder dosage is 95kg/m < 3 > -100 kg/m < 3 >, the river sand dosage is 700kg/m < 3 > -752 kg/m < 3 >, the broken stone dosage is 1164kg/m < 3 > -1187 kg/m < 3 >, the mixing water dosage is 133kg/m < 3 > -140 kg/m < 3 >, the water reducer dosage is 3.4kg/m < 3 > -3.6 kg/m < 3 >, the shrinkage reducing agent dosage is 3.0kg/m < 3 > -3.2 kg/m < 3 >, and the expanding agent dosage is 19kg/m < 3 > -20 kg/m < 3 >.
Preferably, the fiber concrete layer consists of cement, fly ash, slag powder, river sand, broken stone, mixing water, a water reducer, modified polyester fibers and CPA, wherein the cement dosage is 152kg/m 3-160 kg/m3, the fly ash dosage is 99kg/m 3-104 kg/m3, the slag powder dosage is 99kg/m 3-104 kg/m3, the river sand dosage is 697kg/m 3-748 kg/m3, the broken stone dosage is 1120kg/m 3-1182 kg/m3, the mixing water dosage is 133kg/m 3-140 kg/m3, the water reducer dosage is 3.8kg/m 3-4.0 kg/m3, and the modified polyester fibers dosage is 1.0kg/m 3-1.2 kg/m3, and the CPA dosage is 30kg/m 3-32 kg/m3.
Preferably, the thickness ratio of the fibrous concrete layer to the low shrinkage concrete layer is (4-5): 1.
Preferably, the composite concrete layer is formed by casting Shi Jian in a sectional mode, reserved holes are formed in the composite concrete layer, and reinforcing steel bar anti-cracking meshes are buried around the reserved holes.
Preferably, when the thickness of the composite concrete layer is set to be less than or equal to 0.5m, the reinforcing steel bar anti-cracking net sheet is set to be one layer; when the thickness of the composite concrete layer is set to be more than 0.5m, the reinforcing steel bar anti-cracking net sheet is at least set to be two layers.
Preferably, the steel bar anti-cracking net sheet is formed by binding steel bars, the diameter width of the steel bars is between phi 8mm and phi 10mm, and the reinforcement ratio of the length direction and the width direction of the composite concrete layer is between 0.5% and 1.0%.
Preferably, the fiber concrete layer is provided with a protective maintenance layer, and the protective maintenance layer comprises a single-layer plastic film and a double-layer geotextile which are paved on the fiber concrete layer.
Preferably, the protective layer further comprises a single layer of wet geotextile.
Preferably, the fiber concrete layer comprises a plurality of cut blocks, the lengths of the blocks are between 5m and 6m, the width of a gap between every two adjacent blocks is 5mm, and asphalt is filled in the gap.
By adopting the preferable scheme, compared with the prior art, the invention has the following advantages:
1. according to the invention, a layer of low-shrinkage concrete is added between the hardened concrete at the bottom of the surface layer and the fiber concrete of the surface layer to serve as a transition layer between the surface layer concrete and the bottom concrete, so that the shrinkage tensile stress of the surface layer concrete under the action of strong bottom constraint can be remarkably reduced, and the problem of overlarge tensile stress caused by strong bottom constraint is fundamentally solved.
2. According to the composite structure, after the pouring of the low-shrinkage concrete is finished, the fiber concrete layer is immediately poured, the fiber concrete is vibrated before the remodeling time of the low-shrinkage concrete is finished, the low-shrinkage concrete layer and the fiber concrete layer are tightly combined together, the front-back pouring time interval is extremely short, each performance of two layers of concrete can be synchronously and coordinately developed, and the low-shrinkage concrete layer does not form strong constraint on the fiber concrete layer.
3. The thickness ratio of the fiber concrete layer to the low shrinkage concrete layer is 4:1-5:1, the dosage of the low shrinkage concrete in the surface layer is low, and compared with the scheme that the whole surface layer is doped with the shrinkage reducing agent, the composite structure obviously reduces the dosage of the shrinkage reducing agent. Compared with fiber concrete, the water reducer can be reduced in dosage under the same water-cement ratio condition, and the curing is carried out by adopting a conventional process. The composite structure can basically avoid various cracks of the surface concrete, and has high crack control cost performance.
Detailed Description
In order that the above-recited objects, features and advantages of the present invention will be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description. In addition, embodiments of the present application and features of the embodiments may be combined with each other without conflict. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, and the described embodiments are merely some, rather than all, embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, are intended to fall within the scope of the present invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
As shown in fig. 1-2, the present invention provides a cracking prevention structure for a dock face, comprising a composite concrete layer disposed on a rigid substrate of a dock, the composite concrete layer comprising a low shrinkage concrete layer 2 and a fiber concrete layer 1, the low shrinkage concrete layer 2 being disposed between the rigid substrate and the fiber concrete layer 1. The cracking-preventing structure is poured on hard base structures such as wharf breast walls, piers and the like, a composite concrete layer is formed by a fiber concrete layer 1 and a low-shrinkage concrete layer 2, and a wharf surface layer is formed accordingly.
Preferably, the composite concrete layer adopts sectional pouring Shi Jian, the composite concrete layer Shi Jian is rectangular, the length-width ratio of the composite concrete layer poured in a single section is not more than 2, and the thickness is not more than 0.8m, wherein the fiber concrete layer 1 is the upper part of the wharf deck, the low shrinkage concrete layer 2 is the lower part of the wharf deck, and the thickness ratio of the fiber concrete layer 1 to the low shrinkage concrete layer 2 is 4:1-5:1.
Preferably, the composite concrete layer is provided with preformed holes, and reinforcing steel bar anti-cracking meshes 3 arranged in layers are buried around the preformed holes. The preformed hole of the surface layer or the corners of the preformed hole are optimally designed to be round, the periphery of the preformed hole is bound and embedded with a reinforcing steel bar anti-cracking net sheet 3 which is formed by binding reinforcing steel bars with phi 8-10mm, and when the thickness of the surface layer is not more than 0.5m, a layer of reinforcing steel bar anti-cracking net sheet 3 is arranged; when the thickness of the surface layer is more than 0.5m, two layers of reinforcing steel bar anti-cracking meshes 3 are arranged. The reinforcing bar anticracking net piece 3 that sets up on the preformed hole, every layer of reinforcing bar anticracking net piece 3 comprises 8 reinforcing bars, and wherein 4 reinforcing bars are the steel bar frame according to preformed hole shape ligature, preformed hole is circular or square then the steel bar frame ligature be the square, preformed hole is rectangle then the steel bar frame also ligature be rectangle, and 4 are 45 crisscross with the frame as supplementary muscle 4 in addition.
Preferably, the low shrinkage concrete layer 2 and the fiber concrete layer 1 are both poured by adopting a hanging tank or chute process, the low shrinkage concrete layer 2 is directly poured on a hardened concrete hard substrate of a wharf breast wall, a pier and other structures at the bottom of the surface layer, the fiber concrete layer 1 is immediately poured after the pouring of the low shrinkage concrete layer 2 is completed, the vibration Shi Jian of the fiber concrete layer 1 is completed before the remodeling time of the low shrinkage concrete layer 2 is completed, and then heat preservation and moisture preservation maintenance are carried out.
When the fiber concrete layer 1 is poured on the low shrinkage concrete layer 2, the vibrator is vertically inserted into the fiber concrete layer 1 and is inserted into the low shrinkage concrete layer 2, so that the combination of the newly poured concrete and the previously poured concrete is well ensured, and the insertion depth is 30mm-50mm. After the fiber concrete layer 1 is poured, immediately covering and paving a single-layer plastic film and a double-layer geotextile on the concrete surface, and after pouring is finished for 16 hours, covering a single-layer wet geotextile, a single-layer plastic film and a double-layer geotextile for heat preservation and moisture preservation maintenance, wherein the maintenance time is not less than 15 days.
Preferably, the fibrous concrete layer 1 is cut and segmented into blocks by a concrete slotting machine within 16-24 hours after pouring, the length of the blocks is 5m-6m, the width of the kerf is 5mm, the depth is 20mm, fresh water is used for flushing mud after finishing cutting operation, and asphalt is used for slotting after air drying.
Preferably, the low shrinkage concrete layer 2 consists of cement, fly ash, slag powder, river sand, broken stone, mixing water, a water reducer, a shrinkage reducing agent and an expanding agent, wherein the cement dosage is 171kg/m 3-180 kg/m3, the fly ash dosage is 95kg/m 3-100 kg/m3, the slag powder dosage is 95kg/m 3-100 kg/m3, the river sand dosage is 700kg/m 3-752 kg/m3, the broken stone dosage is 1164kg/m 3-1187 kg/m3, the mixing water dosage is 133kg/m 3-140 kg/m3, the water reducer dosage is 3.4kg/m 3-3.6 kg/m3, the shrinkage reducing agent dosage is 3.0kg/m 3-3.2 kg/m3, and the expanding agent dosage is 19kg/m 3-20 kg/m3.
Preferably, the fiber concrete layer 1 consists of cement, fly ash, slag powder, river sand, broken stone, mixing water, water reducer, modified polyester fiber and CPA, wherein the cement dosage is 152kg/m 3-160 kg/m3, the fly ash dosage is 99kg/m 3-104 kg/m3, the slag powder dosage is 99kg/m 3-104 kg/m3, the river sand dosage is 697kg/m 3-748 kg/m3, the broken stone dosage is 1120kg/m 3-1182 kg/m3, the mixing water dosage is 133kg/m 3-140 kg/m3, the water reducer dosage is 3.8kg/m 3-4.0 kg/m3, the modified polyester fiber dosage is 1.0kg/m 3-1.2 kg/m3 and the CPA dosage is 30kg/m 3-32 kg/m3.
Furthermore, the cement used in the low shrinkage concrete layer 2 and the fiber concrete layer 1 is P.O42.5 ordinary Portland cement, the fly ash is class II fly ash, the slag powder is class S95, the river sand is middle sand with the fineness modulus of 2.6-2.9, the broken stone is granite broken stone with 5-25 mm, the water reducing agent is a polycarboxylic acid high-performance water reducing agent, the shrinkage reducing agent is a polyether alcohol shrinkage reducing agent, the fiber is modified polyester fiber, and the CPA is corrosion resistantReinforcing materials. The grade strength of the low shrinkage concrete layer 2 is C35-C45, the slump is 120-160 mm, the 56d electric flux is less than 1000C, and the 90d dry shrinkage is less than 200 multiplied by 10 -6 The heat insulation temperature rise is less than 45 ℃, the remolding time is more than 4.0h under the conditions that the ambient temperature is more than 35 ℃, the remolding time is more than 5h under the conditions that the ambient temperature is 25-35 ℃, and the remolding time is more than 6h under the conditions that the ambient temperature is less than 25 ℃. The fiber concrete layer 1 has the strength grade of C35-C45, the slump of 120-160 mm, the 56d electric flux of less than 1000C, and the 90d dry shrinkage of less than 400 multiplied by 10 -6 The adiabatic temperature rise is less than 45 ℃. According to the wharf surface layer construction form, the crack resistance safety coefficient of the composite construction of the surface layer fiber concrete layer 1 and the low shrinkage concrete layer 2 is calculated to be larger than 1.4 by adopting MIDAS/Civil software.
Example 1
The gravity type wharf deck is divided into blocks with the length of 14m, the width of 17m and the thickness of 0.8m of a single-section deck by adopting the composite construction form of the invention, wherein the thickness of a fiber concrete layer 1 is 0.65m, the thickness of a low shrinkage concrete layer 2 is 0.15m, and the thickness ratio of the fiber concrete layer 1 to the low shrinkage concrete layer 2 is 4.3:1. An anti-cracking phi 8 steel bar anti-cracking net sheet 3 is additionally arranged on the surface layer, the distance between the steel bars is 50mm, and the reinforcement ratio is 0.8%. The shape of the reserved hole 5 of the surface layer is designed to be round, the thickness of the surface layer of the wharf is set to be 0.8m, and two layers of phi 8 reinforcing steel bar anti-cracking meshes 3 are arranged around the reserved hole.
Preparing low shrinkage concrete, wherein the cement consumption is 171kg/m3, the fly ash consumption is 95kg/m3, the slag powder consumption is 95kg/m3, the river sand consumption is 714kg/m3, the broken stone consumption is 1187kg/m3, the mixing water consumption is 133kg/m3, the water reducer consumption is 3.4kg/m3, the shrinkage reducing agent consumption is 3.0kg/m3, and the expanding agent consumption is 19kg/m3. Test Low shrinkage concrete slump of 145mm, compressive Strength of 57.1MPa,56d electric flux of 700C,90d Dry shrinkage of 140X 10 -6 The adiabatic temperature rise is 43.1 ℃, the 28d elastic modulus is 41.1 multiplied by 104MPa, the splitting tensile strength is 4.6MPa, and the remodeling time under different environmental temperature conditions is 4.5h (the environmental temperature is more than 35 ℃) and 5.1h (the environmental temperature is 25 ℃)35 deg.c), 6h (ambient temperature less than 25 deg.c).
Preparing fiber concrete, wherein the cement consumption is 152kg/m3, the fly ash consumption is 99kg/m3, the slag powder consumption is 99kg/m3, the river sand consumption is 711kg/m3, the broken stone consumption is 1182kg/m3, the mixing water consumption is 133kg/m3, the water reducer consumption is 3.8kg/m3, the modified polyester fiber consumption is 1.0kg/m3, and the CPA consumption is 30kg/m3. The slump of the fiber concrete is 155mm, the strength is 55.6MPa, the slump is 120 mm-160 mm, the 56d electric flux is 520C, and the 90d drying shrinkage is 330 multiplied by 10 -6 The adiabatic temperature rise is 41.8 ℃, the 28d elastic modulus is 39.2×104MPa, and the splitting tensile strength is 4.4MPa.
And (3) producing low shrinkage concrete and fiber concrete according to the mixing ratio, pouring by adopting a tank hanging process at the environment temperature of 36.2 ℃, immediately pouring the fiber concrete layer 1 after pouring and vibrating the low shrinkage concrete layer 2, wherein the time interval is 0.8h, and when pouring the fiber concrete layer 1, vertically inserting a vibrator into the fiber concrete layer 1 and inserting the vibrator into the low shrinkage concrete layer 2 until the depth is 35mm. After the fiber concrete layer 1 is poured, immediately covering and paving a layer of plastic film and double-layer geotextile on the surface of the concrete, and after pouring is finished for 16.6 hours, adjusting to cover a layer of wet geotextile, a layer of plastic film and double-layer geotextile for heat preservation and moisture preservation maintenance, wherein the maintenance time is 15d.
And after the fiber concrete layer 1 is poured, cutting and blocking the wharf surface layer by adopting a concrete slotting machine, wherein the blocking length is 5m, the slotting width is 5mm, the slotting depth is 20mm, the slurry is washed clean by fresh water after the cutting operation is finished, and the slot is filled by adopting asphalt after air drying.
According to the gravity wharf structural form, MIDAS/Civil software is adopted to calculate the temperature shrinkage stress of the surface layer, the maximum tensile stress of the composite structure of the fiber concrete layer 1 and the low shrinkage concrete layer 2 is 1.76MPa, the anti-cracking safety coefficient is 1.53, and the anti-cracking requirement is met.
Example 2
The longitudinal length and the transverse width of a certain high pile wharf surface layer are 30m, the thickness is 0.5m, the high pile wharf surface layer is divided into blocks with the length and the width of a single section of the wharf surface layer being 15m and the thickness being 0.5m by adopting the composite structural form of the invention, the thickness of a fiber concrete layer 1 is 0.4m, the thickness of a low shrinkage concrete layer 2 is 0.1m, and the thickness ratio of the fiber concrete layer 1 to the low shrinkage concrete layer 2 is 4:1. An anticracking phi 8 reinforcing steel bar anticracking net sheet 3 is additionally arranged on the surface layer, the spacing between the reinforcing steel bars is 50mm, and the reinforcing steel bar arrangement rate is 0.95%. The shape of the reserved hole 6 of the surface layer is optimally designed into a rounded rectangle, the thickness of the surface layer is 0.5m, and a layer of phi 8 reinforcing steel bar anti-cracking net sheet 3 is arranged around the reserved hole.
Preparing low shrinkage concrete, wherein the cement consumption is 200kg/m3, the fly ash consumption is 100kg/m3, the slag powder consumption is 100kg/m3, the river sand consumption is 737kg/m3, the crushed stone consumption is 1126kg/m3, the mixing water consumption is 140kg/m3, the water reducer consumption is 3.6kg/m3, the shrinkage reducing agent consumption is 3.2kg/m3, and the expanding agent consumption is 20kg/m3. Test Low shrinkage concrete slump of 150mm, compressive Strength of 58.6MPa,56d electric flux of 810C,90d Dry shrinkage of 175X 10 -6 The adiabatic temperature rise is 44 ℃ and the 28d elastic modulus is 41.9X104 MPa, the splitting tensile strength is 4.7MPa, and the remodeling time under different environmental temperature conditions is 4.1h (the environmental temperature is more than 35 ℃), 5.3h (the environmental temperature is 25-35 ℃), and 6.5h (the environmental temperature is less than 25 ℃), respectively.
Preparing fiber concrete, wherein the cement consumption is 160kg/m3, the fly ash consumption is 104kg/m3, the slag powder consumption is 104kg/m3, the river sand consumption is 733kg/m3, the broken stone consumption is 1121kg/m3, the mixing water consumption is 140kg/m3, the water reducer consumption is 4.0kg/m3, the modified polyester fiber consumption is 1.1kg/m3, and the CPA consumption is 32kg/m3. The slump of the fiber concrete is 140mm, the strength is 56.4MPa, the 56d electric flux is 460C, and the 90d drying shrinkage is 360 multiplied by 10 -6 The adiabatic temperature rise is 42.6 ℃, the 28d elastic modulus is 38.4X104 MPa, and the splitting tensile strength is 4.2MPa.
And (3) producing low shrinkage concrete and fiber concrete according to the mixing ratio, pouring by adopting a chute process at the environment temperature of 27.1 ℃, immediately pouring the fiber concrete layer 1 after pouring and vibrating the low shrinkage concrete layer 2, wherein the time interval is 0.5h, and when pouring the fiber concrete layer 1, vertically inserting a vibrator into the fiber concrete layer 1 and inserting the vibrator into the low shrinkage concrete layer 2 until the depth is 30mm. After the fiber concrete layer 1 is poured, immediately covering and paving a layer of plastic film and double-layer geotextile on the surface of the concrete, and after pouring is finished for 16.6 hours, adjusting to cover a layer of wet geotextile, a layer of plastic film and double-layer geotextile for heat preservation and moisture preservation maintenance, wherein the maintenance time is 15d.
After the fiber concrete layer 1 is poured, cutting and blocking the surface layer by adopting a concrete slotting machine, wherein the blocking length is 5m, the slotting width is 5mm, the depth is 20mm, the slurry is washed clean by fresh water after the cutting operation is finished, and the slotting is performed by adopting asphalt after air drying.
According to the construction form of the high pile wharf, MIDAS/Civil software is adopted to calculate the temperature shrinkage stress of the surface layer, the maximum tensile stress of the composite structure of the fiber concrete layer 1 and the low shrinkage concrete layer 2 is 1.61MPa, the anti-cracking safety coefficient is 1.49, and the anti-cracking requirement is met.
The present invention is not limited to the preferred embodiments, and any modifications, equivalent variations and modifications made to the above embodiments according to the technical principles of the present invention are within the scope of the technical proposal of the present invention.